A neuroanatomical research laboratory has been equipped for the newly developed fiber tracing techniques of tritiated amino acid autoradiography and horseradish peroxidase (HRP) histochemistry. Injections of the tracer chemicals into discrete regions of the rat brain are made by iontophoresis. The autoradiographic material is intended to show the efferent projections of various midline and intralaminar thalamic cell groups over widespread regions of the cerebral cortex. Special attention will be paid to the laminar distribution of thalamic afferents in the cortex. The HRP material can provide details about the sources of the cortical projections. Taken together, these data may provide structural evidence for mechanisms of thalamocortical integration that have not previously been appreciated.